JP2014071387A - Photoresist composition, method for forming resist pattern, polymer, compound and production method of compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoresist composition excellent in EL (exposure latitude) performance, LWR (line width roughness) performance, CDU (critical dimension uniformity) performance and top loss suppressing property.SOLUTION: The photoresist composition comprises [A] a polymer having a structural unit (I) expressed by formula (1) and [B] an acid generator. In formula (1), Rrepresents a monovalent hydrocarbon group having 1 to 10 carbon atoms; Rrepresents a monovalent hydrocarbon group having 1 to 20 carbon atoms. The [A] polymer preferably further includes a structural unit (II) expressed by formula (2).

Description

  The present invention relates to a photoresist composition, a resist pattern forming method, a polymer, a compound, and a method for producing the compound.

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, further miniaturization of resist patterns in the lithography process is required, and various photoresist compositions are being studied. Such a photoresist composition generates an acid in an exposed portion by irradiation with exposure light such as deep ultraviolet rays such as an ArF excimer laser or an electron beam, and a developer solution for exposed and unexposed portions by the catalytic action of this acid. A difference in the dissolution rate with respect to is formed, and a resist pattern is formed on the substrate.

  Such a photoresist composition not only has excellent resolution and the like, but also has excellent LWR (Line Width Roughness) performance, CDU (Critical Dimension Uniformity) performance, etc., and EL performance (Exposure Latitude: exposure margin) performance. Therefore, it is required to obtain a highly accurate pattern with a high yield. In response to this requirement, various structures of the polymer contained in the photoresist composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the adhesion of the resist pattern to the substrate can be improved. It is known that these performances can be improved while improving the performance (see JP-A-11-212265, JP-A-2003-5375, and JP-A-2008-83370).

  However, at present, when the miniaturization of the resist pattern is progressing to a level of 45 nm or less, the required level of the performance is further increased, and the conventional photoresist composition satisfies the above requirements. Is not done. Moreover, in the conventional photoresist composition, there is a disadvantage that a pattern top loss may occur, and it may be difficult to obtain a pattern having excellent cross-sectional shape rectangularity.

JP 11-212265 A JP 2003-5375 A JP 2008-83370 A

  This invention is made | formed based on the above situations, The objective is to provide the photoresist composition excellent in EL performance, LWR performance, CDU performance, and top loss suppression property.

（式（１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２は、炭素数１〜１０の１価の炭化水素基である。Ｒ^３は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の炭化水素基である。複数のＲ^３は、同一でも異なっていてもよい。但し、少なくとも一つのＲ^３が、炭素数１〜２０の１価の炭化水素基である。ｋは、０〜４の整数である。ｍは、０〜４の整数である。但し、１≦ｋ＋ｍ≦４を満たす。） The invention made to solve the above problems is
[A] A photoresist composition containing a structural unit (I) represented by the following formula (1) (hereinafter also referred to as “[A] polymer”), and [B] a photoresist composition containing an acid generator. is there.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied.

The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film using the photoresist composition;
(2) a step of exposing the resist film; and (3) a step of developing the exposed resist film.

（式（１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２は、炭素数１〜１０の１価の炭化水素基である。Ｒ^３は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の炭化水素基である。複数のＲ^３は、同一でも異なっていてもよい。但し、少なくとも一つのＲ^３が、炭素数１〜２０の１価の炭化水素基である。ｋは、０〜４の整数である。ｍは、０〜４の整数である。但し、１≦ｋ＋ｍ≦４を満たす。） The polymer of the present invention has a structural unit (I) represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied.

（式（ｉ）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２は、炭素数１〜１０の１価の炭化水素基である。Ｒ^３は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の炭化水素基である。複数のＲ^３は、同一でも異なっていてもよい。但し、少なくとも一つのＲ^３が、炭素数１〜２０の１価の炭化水素基である。ｋは、０〜４の整数である。ｍは、０〜４の整数である。但し、１≦ｋ＋ｍ≦４を満たす。） The compound of the present invention (hereinafter also referred to as “compound (i)”) is represented by the following formula (i).

(In formula (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied.

（式（ａ）、（ｂ）、（ｃ）及び（ｉ）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２は、炭素数１〜１０の１価の炭化水素基である。Ｒ^３は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の炭化水素基である。複数のＲ^３は、同一でも異なっていてもよい。但し、少なくとも一つのＲ^３が、炭素数１〜２０の１価の炭化水素基である。ｋは、０〜４の整数である。ｍは、０〜４の整数である。但し、１≦ｋ＋ｍ≦４を満たす。Ｙは、ハロゲン原子である。Ｚは、ハロゲン原子、−ＯＨ又は−ＯＣＯＲ’である。Ｒ’は、炭素数１〜２０の１価の炭化水素基である。） The method for producing the compound of the present invention comprises:
(A) A step of obtaining a compound represented by the following formula (b) by a cyclization reaction of the compound represented by the following formula (a), and (B) the following formula (b) obtained in the step (A) It is a manufacturing method of the compound represented by the following formula (i) which has the process of making the compound represented and the compound represented by the following formula (c) react.

(In the formulas (a), (b), (c) and (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is 1 having 1 to 10 carbon atoms. R ³ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a plurality of R ³ may be the same or different. , At least one R ³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, k is an integer of 0 to 4. m is an integer of 0 to 4, provided that 1 ≦ k + m ≦ 4 is satisfied, Y is a halogen atom, Z is a halogen atom, —OH or —OCOR ′, and R ′ is a monovalent hydrocarbon group having 1 to 20 carbon atoms.)

  Here, the “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

  According to the photoresist composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern having a small LWR and a small top loss while exhibiting a wide EL. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a monomer for the polymer. According to the method for producing a compound of the present invention, the compound can be produced simply and with good yield. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Photoresist composition>
The photoresist composition contains a [A] polymer and a [B] acid generator. The photoresist composition may contain [C] acid diffusion controller, [D] fluorine atom-containing polymer (hereinafter also referred to as “[D] polymer”), and [E] solvent as suitable components. In addition, other optional components may be contained as long as the effects of the present invention are not impaired.
Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). The said photoresist composition is excellent in EL performance, LWR performance, CDU performance, and top loss suppression property because [A] polymer has structural unit (I).
The reason why the photoresist composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, in the lactone ring in the structural unit (I), the R ² group is bonded to the carbon atom bonded to the oxygen atom of the ester group, and at least one group (R ³ ) is bonded to the carbon atom constituting the lactone ring. And a specific structure in which two hydrogen atoms are bonded to a carbon atom adjacent to the oxygen atom of the lactone ring to form a methylene group. It is considered that the lactone ring has a structure having these two kinds of groups and a methylene group, so that the ring-opening reactivity with respect to an alkaline developer is appropriately increased. As a result, the resolution and the like of the photoresist composition are improved, and as a result, the EL performance, LWR performance, and CDU performance are improved. In addition, since the ring-opening reactivity is lower than in the case of an unsubstituted lactone-yl group, it is suppressed from dissolving in the developer up to the pattern top of the unexposed area, and the top loss is suppressed. As a result, the performance of CDU and the like is improved.

[A] The polymer is a structural unit other than the structural unit (I), a structural unit (II) represented by the following formula (2), and a structural unit other than the structural unit (I). And a structural unit (III) containing at least one selected from the group consisting of sultone structures, and may have other structural units other than the structural units (I) to (III). [A] The polymer may have one or more of the above structural units.
Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is represented by the following formula (1).

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. A plurality of R ³ may be the same or different. However, at least one R ³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. k is an integer of 0-4. m is an integer of 0-4. However, 1 ≦ k + m ≦ 4 is satisfied.

R ¹ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ² include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms and a monovalent alicyclic ring having 3 to 10 carbon atoms. And a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

Examples of the monovalent chain hydrocarbon group include:
Alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl and n-pentyl;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.

Examples of the monovalent alicyclic hydrocarbon group include:
Monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent aromatic hydrocarbon group include:
Aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, and phenylpropyl group.

Among these, R ² is preferably a monovalent chain hydrocarbon group, more preferably an alkyl group, and an alkyl group having 1 to 4 carbon atoms from the viewpoint of appropriately increasing the above-described ring-opening reactivity. More preferred are methyl group and ethyl group.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ³ include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent alicyclic ring having 3 to 20 carbon atoms. And a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the chain hydrocarbon group, alicyclic hydrocarbon group and aromatic hydrocarbon group include the same groups as the groups exemplified as R ² above.

Among these, R ³ is preferably a monovalent chain hydrocarbon group, more preferably an alkyl group, and an alkyl group having 1 to 4 carbon atoms from the viewpoint of appropriately increasing the above-described ring-opening reactivity. More preferred is a methyl group.

As the position to which R ³ is bonded, the carbonyl of the lactone ring in formula (1) from the viewpoint of increasing the above-described ring-opening reactivity more moderately and from the viewpoint of the ease of synthesis of the monomer that gives the structural unit (I). The α position of the group is preferred.
The number of R ³ as a monovalent hydrocarbon group is preferably 1 to 3 and more preferably 1 or 2 from the viewpoint of appropriately increasing the above-described ease of ring opening.

As said k, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.
As said m, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 1 is further more preferable.
As said k + m, the integer of 1-3 is preferable, 1 or 2 is more preferable, and 1 is further more preferable.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-17) (hereinafter also referred to as “structural units (I-1) to (I-17)”). Etc.

In the formulas (1-1) to (1-17), R ¹ has the same meaning as the formula (1).

  Among these, the structural unit (I-1) to the structural unit (I-12) are preferable, the structural unit (I-1) to the structural unit (I-5) are more preferable, and the structural unit (I-1) to (I-3) is more preferable.

  As a minimum of the content rate of structural unit (I), 1 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 10 mol% is more preferable, 18 mol% is further more preferable, 25 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 80 mol% is preferable, 75 mol% is more preferable, 65 mol% is further more preferable, 55 mol% is especially preferable. By making the said content rate into the said range, EL performance, LWR performance, CDU performance, and top loss suppression property of the said photoresist composition can be improved. When the content ratio is less than the lower limit, the above effect may not be sufficiently exhibited. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

  Examples of the compound giving structural unit (I) include compound (i). Compound (i) is represented by the following formula (i).

In said formula (i), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. A plurality of R ³ may be the same or different. However, at least one R ³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. k is an integer of 0-4. m is an integer of 0-4. However, 1 ≦ k + m ≦ 4 is satisfied.

  Examples of the compound (i) include compounds represented by the following formulas (i1) to (i17) (hereinafter also referred to as “compounds (i1) to (i17)”).

In the above formulas (i1) to (i17), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, the compounds (i1) to (i12) are preferable, the compounds (i1) to (i5) are more preferable, and the compounds (i1) to (i3) are more preferable.

[A] As described later, the polymer [A] can be obtained by radical polymerization or the like together with a monomer that gives the structural unit (I) and a monomer that gives another structural unit as necessary. The production method of the compound (i) giving the structural unit (I) is, for example, as follows:
(A) A step of obtaining a compound represented by the following formula (b) by a cyclization reaction of the compound represented by the following formula (a), and (B) the following formula (b) obtained in the step (A) And a step of reacting the compound represented by the following formula (c).
According to this production method, compound (i) can be produced easily and with high yield from the compound represented by the following formula (a) according to the following scheme.

In the above scheme, R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. A plurality of R ³ may be the same or different. However, at least one R ³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. k is an integer of 0-4. m is an integer of 0-4. However, 1 ≦ k + m ≦ 4 is satisfied. Y is a halogen atom. Z is a halogen atom, —OH or —OCOR ′. R ′ is a monovalent hydrocarbon group having 1 to 20 carbon atoms.

  The hydroxylactone compound represented by the above formula (b) is obtained by cyclizing the haloketone compound represented by the above formula (a) in a solvent such as tetrahydrofuran in the presence of metallic zinc. Next, the obtained hydroxylactone compound is reacted with a (meth) acrylic acid halide represented by the above formula (c) in a solvent such as acetonitrile in the presence of a base such as triethylamine. (I) is generated. After concentrating the reaction solution, compound (i) can be isolated by appropriate treatment such as liquid separation operation, distillation, recrystallization, column chromatography and the like.

  Examples of the halogen atom represented by Y include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, from the viewpoint of increasing the reaction yield, a chlorine atom and a bromine atom are preferable, and a bromine atom is more preferable.

[Structural unit (II)]
The structural unit (II) is a structural unit represented by the following formula (2). The group represented by —CR ⁵ R ⁶ R ⁷ in the structural unit (II) is an acid dissociable group. The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a carboxy group and is dissociated by the action of an acid. In the photoresist composition, the [A] polymer has the structural unit (II), thereby improving sensitivity and resolution, and as a result, improving EL performance, LWR performance, CDU performance, and top loss suppression. Can be made.

In the formula (2), R ⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁵ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ⁶ and R ⁷ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents an alicyclic structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded to each other.

R ⁴ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II).

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ⁵ , R ⁶ and R ⁷ include, for example,
Alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ⁴ , R ⁵ and R ⁶ include, for example,
Monocyclic cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group;
A monocyclic cycloalkenyl group such as a cyclopentenyl group and a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted and represented together with the carbon atom to which these groups are combined with each other include, for example,
Monocyclic cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

  As the structural unit (II), structural units represented by the following formulas (2-1) to (2-4) (hereinafter also referred to as “structural units (II-1) to (II-4)”) are preferable. .

In the above formulas (2-1) to (2-4), R ^{4 to} R ⁹ have the same meaning as the above formula (2). i and j are each independently an integer of 1 to 4.

  Examples of the structural units (II-1) to (II-4) include structural units represented by the following formulas.

In said formula, R < ⁴ > is synonymous with the said Formula (2).

  As structural unit (II), structural unit derived from 1-alkyl-1-cyclopentyl (meth) acrylate, structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate, 2- (adamantan-1-yl ) A structural unit derived from propan-2-yl (meth) acrylate and a structural unit derived from 2-cyclohexylpropan-2-yl (meth) acrylate are preferred.

  As a content rate of structural unit (II), 10 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-70 mol% are more preferable, 25 mol% -60 mol% is more preferable. By making the said content rate into the said range, the sensitivity and resolution of the said photoresist composition improve more, and as a result, EL performance, LWR performance, CDU performance, and top loss suppression property improve. When the said content rate is less than the said minimum, the pattern formation property of the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the adhesiveness to the board | substrate of a resist pattern may fall.

[Structural unit (III)]
The structural unit (III) is a structural unit other than the structural unit (I) and includes at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. [A] The polymer further includes the structural unit (III) in addition to the structural unit (I), so that the solubility in the developer can be further adjusted. EL performance, LWR performance, CDU performance, and top loss suppression can be improved. Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved.

  Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, R ^L1 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, the structural unit (III) is preferably a structural unit containing a norbornane lactone structure, a structural unit containing a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, or a structural unit containing a norbornane sultone structure. A structural unit derived from yl (meth) acrylate, a structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, a structural unit derived from γ-butyrolactone-yl-1,1-cyclohexanediyl (meth) acrylate, Structural unit derived from 1,4-dimethyl-γ-butyrolactone-yl (meth) acrylate, structural unit derived from 1,2-dimethyl-γ-butyrolactone-yl (meth) acrylate, γ-butyrolactone-yl (meth) Structural unit derived from acrylate More preferred are structural units derived from ethylene carbonate-ylmethyl (meth) acrylate, structural units derived from norbornane sultone-yl (meth) acrylate, and structural units derived from norbornane sultone-yloxycarbonylmethyl (meth) acrylate.

  As a content rate of structural unit (III), 0 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 15 mol%-65 mol% are more preferable, 25 mol% More preferred is ˜55 mol%. By making the said content rate into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition can be improved more. When the said content rate is less than the said minimum, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (III). Examples of other structural units include structural units containing a hydroxy group.

  Examples of the structural unit containing a hydroxy group include a structural unit represented by the following formula.

In the above formula, R ^B is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  As a content rate of the structural unit containing the said hydroxyl group, 30 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, 20 mol% or less is preferable, and 3 mol%-15 mol% are preferable. Further preferred. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

  [A] The polymer may have other structural units in addition to the above structural units. As a content rate of the said other structural unit, 20 mol% or less is preferable and 10 mol% or less is more preferable.

  [A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more in the total solid content of the photoresist composition.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing a monomer giving each structural unit in a suitable solvent using a radical polymerization initiator or the like.

  Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropylene). Pionitrile), azo radical initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroperoxide, And peroxide radical initiators such as cumene hydroperoxide. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. The solvent used for these polymerizations may be used alone or in combination of two or more.

  As reaction temperature in the said superposition | polymerization, 40 to 150 degreeC and 50 to 120 degreeC are preferable normally. The reaction time is usually preferably 1 hour to 48 hours and 1 hour to 24 hours.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, 3,000 or more and 20,000 or less are more preferable, and 5,000 or more and 15,000 are particularly preferable. [A] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said photoresist composition improve. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may deteriorate.

  [A] The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually from 1 to 5, preferably from 1 to 3, more preferably from 1 to 2. .

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (above, manufactured by Tosoh)
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. Since the acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of the [A] polymer in the developer containing the organic solvent is reduced, A negative resist pattern can be formed from the photoresist composition. The content of the [B] acid generator in the photoresist composition is, for example, a low molecular compound form (hereinafter referred to as “ [B] also referred to as “acid generator”), in the form of acid generating groups incorporated as part of the polymer, or in both forms.

  [B] Examples of the acid generator include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, and diazoketone compounds.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4 -Cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyl Diphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonyl Phenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafur B ethanesulfonate, 4-methanesulfonyl-phenyl camphorsulfonate, triphenylphosphonium 1,1,2,2-Fluoro-6- (1-adamantanecarbonyloxy) - hexane-1-sulfonate, and the like.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Ni-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Torahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate , 1- (3,5-dimethyl-4 Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxy Phenyl) tetrahydrothiophenium camphorsulfonate and the like.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoro-ethanone Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide etc. can be mentioned.

  [B] The acid generator is preferably an acid generator represented by the following formula (3). [B] When the acid generator has the following structure, the diffusion length of the acid generated by exposure in the resist film is appropriately shortened by the interaction with the structural unit (I) of the polymer [A]. As a result, the EL performance, LWR performance, CDU performance, and top loss suppression of the photoresist composition can be improved.

In the above formula (3), R ⁸ is a monovalent group containing an alicyclic structure having 7 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members. R ⁹ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent photodegradable onium cation.

The “number of ring members” in R ⁸ means the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure. In the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up the ring.

Examples of the monovalent group containing an alicyclic structure having 7 or more ring members represented by R ⁸ include:
A monocyclic cycloalkyl group such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members represented by R ⁸ include:
A group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
Nitrogen atom-containing heterocyclic groups such as azacycloheptyl group and diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The number of ring members of the group represented by R ⁸ is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the diffusion length of the acid described above becomes more appropriate.

R ⁸ is preferably a monovalent group containing an alicyclic structure having 9 or more ring members, or a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, such as an adamantyl group or a hydroxyadamantyl group. , A norbornanelactone-yl group, and a 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group are more preferable, and an adamantyl group is more preferable.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ⁹ include one hydrogen atom of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. Examples include groups in which the above is substituted with a fluorine atom.
Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group, and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent photodegradable onium cation represented by X ⁺ is a cation that decomposes upon exposure to exposure light. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the photodegradable onium cation and a sulfonate anion. Examples of the monovalent photodegradable onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. And radiation-decomposable onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (X-1), a tetrahydrothiophenium cation represented by the following formula (X-2), and an iodonium cation represented by the following formula (X-3) preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, substituted or unsubstituted. aromatic hydrocarbon group having 6 to 12 carbon atoms, a or a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or two or more are combined with each other configured ring of these groups . R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.
In the above formula (X-2), R ^b1 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon having 6 to 8 carbon atoms. It is a group. k4 is an integer of 0-7. If R ^b1 is plural, the plurality of R ^b1 may be the same or different, and plural R ^b1 may represent a constructed ring aligned with each other. R ^b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0-6. If R ^b2 is plural, the plurality of R ^b2 may be the same or different, and plural R ^b2 may represent a keyed configured ring structure. q is an integer of 0-3.
In the above formula (X-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^{c1, R} c2, ^R when ^R and ^{R S} is plural respective plurality of ^{R c1,} R c2, ^{R R} and ^{R S} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and n-butyl. Groups and the like.
Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an i-propyl group, an i-butyl group, a sec-butyl group, Examples include t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group; benzyl group And aralkyl groups such as a phenethyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^b1 and R ^b2 include a phenyl group, a tolyl group, and a benzyl group.

Examples of the substituent that may substitute the hydrogen atom of the alkyl group and aromatic hydrocarbon group include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, and a cyano group. Group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like.
Among these, a halogen atom is preferable and a fluorine atom is more preferable.

R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an unsubstituted linear or branched alkyl group, a fluorinated alkyl group, and an unsubstituted monovalent aromatic hydrocarbon group. , —OSO ₂ —R ″ and —SO ₂ —R ″ are preferred, fluorinated alkyl groups, unsubstituted monovalent aromatic hydrocarbon groups are more preferred, and fluorinated alkyl groups are more preferred. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As k1, k2, and k3 in the formula (X-1), integers of 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is more preferable.
As k4 in the formula (X-2), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 1 is more preferable. k5 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.
As k6 and k7 in the formula (X-3), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

  Examples of the acid generator represented by the above formula (3) include compounds represented by the following formulas (3-1) to (3-10) (hereinafter referred to as “compounds (3-1) to (3-10)”. ) ")) And the like.

  [B] Among these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt or a tetrahydrothiophenium salt, and the compounds (3-1) to (3-4), (3-6), (3-9) and (3-10) are more preferable, and compounds (3-1) to (3-3) are particularly preferable.

  [B] As the content of the acid generator, when the [B] acid generator is a [B] acid generator, the [A] polymer 100 is used from the viewpoint of ensuring the sensitivity and developability of the photoresist composition. 0.1 parts by mass or more and 30 parts by mass or less are preferable, 0.5 parts by mass or more and 20 parts by mass or less are more preferable, and 1 part by mass or more and 15 parts by mass or less are more preferable. [B] By making content of an acid generator into the said range, the sensitivity and developability of the said photoresist composition improve. [B] 1 type (s) or 2 or more types can be used for an acid generator.

<[C] Acid diffusion controller>
The said photoresist composition may contain a [C] acid diffusion control body as needed.
[C] The acid diffusion control body controls the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film and suppresses undesirable chemical reaction in the non-exposed region, and the resulting photoresist. The storage stability of the composition is further improved, the resolution as a resist is further improved, and changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, thereby improving process stability. An excellent photoresist composition is obtained. [C] As a form of inclusion in the photoresist composition of the acid diffusion controller, a form of a free compound (hereinafter referred to as “[C] acid diffusion controller” as appropriate) was incorporated as part of the polymer. It may be in the form or both forms.

  [C] Examples of the acid diffusion controller include a compound represented by the following formula (4) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”). , “Nitrogen-containing compound (II)”, compounds having three nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. Can be mentioned.

In the above formula (4), R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. .

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. Can be mentioned.

  Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and the like.

  Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. Can be mentioned.

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like. .

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N- (undecylcarbonyloxyethyl) morpholine; pyrazine and pyrazole.

  Moreover, the compound which has an acid dissociable group can also be used as said nitrogen-containing organic compound. Examples of the nitrogen-containing organic compound having such an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl- 2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) Examples thereof include diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like.

  Further, as the [C] acid diffusion control agent, a photodegradable base that is exposed to light and generates a weak acid by exposure can also be used. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (5-1), an iodonium salt compound represented by the following formula (5-2), and the like.

In the above formulas (5-1) and (5-2), R ^{15 to} R ¹⁹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ⁻ and Q ⁻ are each independently an anion represented by OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or the following formula (5-3). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (5-3), R ²⁰ represents a linear or branched alkyl group having 1 to 12 carbon atoms in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 carbon atom. It is a -12 linear or branched alkoxyl group. u is an integer of 0-2.

  As said photodegradable base, the compound etc. which are represented by a following formula are mentioned, for example.

  Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, further preferably triphenylsulfonium salicylate, triphenylsulfonium 10-camphor sulfonate, and triphenylsulfonium 10-camphor. Sulfonate is particularly preferred.

  [C] The content of the acid diffusion controller is 0 to 20 parts by mass with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. Preferably, 0.1 mass part-15 mass parts are more preferable, and 0.3 mass part-10 mass parts are further more preferable. [C] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the photoresist composition may decrease.

<[D] Polymer>
[D] The polymer is a fluorine atom-containing polymer (except for those corresponding to the [A] polymer). When the photoresist composition contains a [D] polymer, when the resist film is formed, the distribution is unevenly distributed near the resist film surface due to the oil-repellent characteristics of the fluoropolymer in the film. It is possible to prevent the acid generator, the acid diffusion controller and the like from being eluted into the immersion medium during immersion exposure. Further, due to the water-repellent characteristics of the [D] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the said photoresist composition contains a [D] polymer, the resist film suitable for an immersion exposure method can be formed.

  [D] The polymer is not particularly limited as long as it is a polymer having fluorine atoms, but the fluorine atom content (% by mass) is higher than that of the [A] polymer in the photoresist composition. preferable. [A] When the fluorine atom content is higher than that of the polymer, the degree of uneven distribution described above becomes higher, and characteristics such as water repellency and elution suppression of the resulting resist film are improved.

[D] The fluorine atom content of the polymer is preferably 1% by mass or more, more preferably 2% by mass to 60% by mass, further preferably 4% by mass to 40% by mass, and 7% by mass to 30% by mass. Particularly preferred. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. In addition, the fluorine atom content rate (mass%) of a polymer can obtain | require the structure of a polymer by < ¹³ > C-NMR spectrum measurement, and can calculate it from the structure.

  [D] The polymer preferably has at least one selected from the group consisting of the following structural unit (Da) and structural unit (Db). [D] The polymer may have one or more structural units (Da) and structural units (Db).

[Structural unit (Da)]
The structural unit (Da) is a structural unit represented by the following formula (6a). [D] A polymer can adjust a fluorine atom content rate by having a structural unit (Da).

In said formula (6a), ^RD is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—. R ^E is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom. It is.

The chain hydrocarbon group having 1 to 6 carbon atoms and having at least one fluorine atom represented by R ^E, for example, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, perfluoroethyl Group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro Examples include n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms and having at least one fluorine atom represented by R ^E, for example, monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl , Difluorocyclopentyl group, perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Examples of the monomer that gives the structural unit (Da) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and 2,2,2-trifluoro. Ethyloxycarbonylmethyl (meth) acrylic acid ester, perfluoroethyl (meth) acrylic acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (Meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (Meth) acrylic acid ester, 1- (2,2,3,3,4,4,5,5-octaful Lopentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, monofluorocyclopentyl (meth) Acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic Acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl Meth) acrylic acid esters, fluoro tricyclodecyl (meth) acrylate, fluoro tetracyclododecene decyl (meth) acrylic acid ester.
Among these, 2,2,2-trifluoroethyloxycarbonylmethyl (meth) acrylic acid ester is preferable.

  As a content rate of a structural unit (Da), 5 mol%-95 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 10 mol%-90 mol% are more preferable, 30 mol% More preferred is ~ 85 mol%. By setting such a content ratio, a higher dynamic contact angle on the resist film surface can be expressed at the time of immersion exposure.

[Structural unit (Db)]
The structural unit (Db) is a structural unit represented by the following formula (6b). Since the [D] polymer has a structural unit (Db) and becomes hydrophobic, the dynamic contact angle of the resist film surface formed from the photoresist composition can be further improved.

In said formula (6b), R ^<F> is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ²¹ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or a terminal at the R ²² side of R ²¹ Also includes a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent organic group. R ²² is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a divalent chain hydrocarbon group having 1 to 20 carbon atoms and having at least one fluorine atom. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent organic group. * ^Indicates a binding site that binds to ^{R 21.} R ²³ is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, a plurality of R ²² , X ² , A ¹ and R ²³ may be the same or different.

When R ²³ is a hydrogen atom, it is preferable in that the solubility of [D] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ²³ include an acid dissociable group, an alkali dissociable group, or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

  Examples of the structural unit (Db) include structural units represented by the following formulas (6b-1) to (6b-3).

In the above formulas (6b-1) to (6b-3), R ^{21 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F , X ² , R ²³ and s are as defined in the above formula (6b). When s is 2 or 3, the plurality of X ² and R ²³ may be the same or different.

  As a content rate of the said structural unit (6b), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 5 mol%-85 mol% are more preferable, 10 mol % To 80 mol% is more preferable. By setting it as such a content rate, the resist film surface formed from the said photoresist composition can improve the fall degree of a dynamic contact angle in alkali image development.

[Structural unit (Dc)]
[D] The polymer may have a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (Dc)”) in addition to the structural units (Da) and (Db) ( However, those corresponding to the structural unit (Db) are excluded). [D] When the polymer has the structural unit (Dc), the shape of the resulting resist pattern becomes better. Examples of the structural unit (Dc) include the structural unit (II) in the above-described [A] polymer.

  As a content rate of the said structural unit (Dc), 5 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 10 mol%-70 mol% are more preferable, 15 mol% -60 mol% is more preferable, and 15 mol%-50 mol% is especially preferable. If the content ratio of the structural unit (Dc) is less than the lower limit, development defects in the resist pattern may not be sufficiently suppressed. When the content ratio of the structural unit (Dc) exceeds the upper limit, the hydrophobicity of the resulting resist film surface may be lowered.

[Other structural units]
In addition to the above structural unit, the [D] polymer includes, for example, a structural unit containing at least one structure selected from the group consisting of a structural unit containing an alkali-soluble group, a lactone structure, a cyclic carbonate structure, and a sultone structure. And may have other structural units such as a structural unit containing an alicyclic group. As said alkali-soluble group, a carboxy group, a sulfonamide group, a sulfo group etc. are mentioned, for example. Examples of the structural unit having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure include the structural unit (III) in the above-described [A] polymer.

  As a content rate of said other structural unit, it is 30 mol% or less normally with respect to all the structural units which comprise a [D] polymer, and 20 mol% or less is preferable. If the content ratio of the other structural unit exceeds the upper limit, the pattern forming property of the photoresist composition may be deteriorated.

  As content of [D] polymer in the said photoresist composition, 0-20 mass parts is preferable with respect to 100 mass parts of [A] polymer, and 0.5 mass part-15 mass parts are more preferable. 1 mass part-10 mass parts are further more preferable. [D] When the content of the polymer exceeds the above upper limit, the pattern forming property of the photoresist composition may be lowered.

<[E] solvent>
The photoresist composition usually contains an [E] solvent. [E] The solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, and the optionally contained [C] acid diffusion controller.

  [E] Examples of the solvent include alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, hydrocarbon solvents, and the like.

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

As an ether solvent, for example,
Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether) are exemplified.

Examples of the ketone solvent include acetone, butanone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), and ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone:
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

Examples of the amide solvent include cyclic amide solvents such as N, N′-dimethylimidazolidinone and N-methylpyrrolidone;
Examples thereof include chain amide solvents such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, and N-methylpropionamide.

Examples of ester solvents include:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxy acetate Acetate solvents such as butyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, and n-nonyl acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol partial ether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
lactone solvents such as γ-butyrolactone and valerolactone;
Carbonate solvents such as diethyl carbonate, ethylene carbonate, propylene carbonate;
Glycol acetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetoacetate, methyl lactate, ethyl lactate N-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

Examples of the hydrocarbon solvent include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, and cyclohexane. , Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents and the like.

  Among these, ester solvents and ketone solvents are preferable, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone solvents are more preferable, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are more preferable. . The photoresist composition may contain one or more [E] solvents.

<Other optional components>
The photoresist composition may contain other optional components in addition to the above [A] to [E]. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds, and sensitizers. Each of these other optional components may be used alone or in combination of two or more.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Manufactured by Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of surfactant in the said photoresist composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(Alicyclic skeleton-containing compound)
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. The content of the alicyclic skeleton-containing compound in the photoresist composition is usually 5 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

(Sensitizer)
The sensitizer exhibits an effect of increasing the amount of acid generated from the [B] acid generator and the like, and has an effect of improving the “apparent sensitivity” of the photoresist composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used alone or in combination of two or more. As content of the sensitizer in the said photoresist composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing photoresist composition>
In the photoresist composition, for example, a [A] polymer, a [B] acid generator, a [C] acid diffusion controller, an optional component contained as necessary, and a [E] solvent are mixed at a predetermined ratio. Can be prepared. The photoresist composition is preferably filtered, for example, with a filter having a pore size of about 0.2 μm after mixing. As solid content concentration of the said photoresist composition, it is 0.1 mass%-50 mass% normally, 0.5 mass%-30 mass% are preferable, and 1 mass%-20 mass% are more preferable.

<Resist pattern formation method>
The resist pattern forming method is:
(1) A step of forming a resist film using the photoresist composition;
(2) a step of exposing the resist film; and (3) a step of developing the exposed resist film.

  According to the resist pattern forming method, since the above-described photoresist composition is used, a resist pattern with a small LWR and a small top loss can be formed while exhibiting a wide EL. Hereinafter, each step will be described.

[(1) Process]
In the step (1), a resist film is formed using the photoresist composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the application method include spin coating (spin coating), cast coating, roll coating, and the like. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. As PB temperature, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film to be formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

  When immersion exposure is performed and the photoresist composition does not contain a water-repellent polymer additive, direct contact between the immersion liquid and the resist film is performed on the formed resist film. For the purpose of avoiding this, an immersion protective film that is insoluble in the immersion liquid may be provided. Examples of the immersion protective film include a solvent peeling type protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), and a developer peeling type that peels off simultaneously with the development in the step (3). Any of the protective films (see, for example, WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

[(2) Process]
In the step (2), the resist film formed in the step (1) is exposed by irradiating exposure light through a photomask (in some cases through an immersion medium such as water). Examples of the exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and γ rays; charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. Among these, far ultraviolet rays and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), and electron beams are more preferable, and ArF excimer laser light and electron beams are more preferable.

  When exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by exposure is dissociated. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. As PEB temperature, it is 50 to 180 degreeC normally, and 80 to 130 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[(3) Process]
In step (3), the resist film exposed in step (2) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with water or a rinse solution such as alcohol and then dry.

As a developer used for the above development,
In the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine , Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4 .3.0] -5 aqueous solution in which at least one alkaline compound such as 5-nonene is dissolved. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.
In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents can be mentioned. Examples of the organic solvent include one or more of the solvents listed as the [E] solvent of the above-described photoresist composition. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. Examples of components other than the organic solvent in the developer include water and silicone oil.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

<Polymer>
The said polymer is a polymer which has structural unit (I) represented by the said Formula (1). Since the polymer has the above-mentioned properties, it can be suitably used as a polymer component of the photoresist composition. The photoresist composition containing the polymer has EL performance, LWR performance, CDU performance, and top loss. Excellent suppression.

<Compound>
The compound is a compound represented by the above formula (i). Since the said compound has the above-mentioned property, it can be used suitably as a raw material monomer of the said polymer.

<Method for producing compound>
The method for producing the compound is as follows:
(A) a step of obtaining a compound represented by the above formula (b) by cyclization reaction of the compound represented by the above formula (a), and (B) the above formula (b) obtained in the step (A). It is a manufacturing method of the compound represented by the said Formula (i) which has the process of making the compound represented and the compound represented by the said formula (c) react.
According to the manufacturing method of the said compound, the said compound can be manufactured simply and with a sufficient yield.

  The said polymer, the said compound, and the manufacturing method of the said compound are demonstrated in the item of the said [A] polymer.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The measuring method of various physical property values is shown below.

[Mw and Mn]
Mw and Mn of the polymer were measured by GPC under the following conditions.
GPC column: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (above, manufactured by Tosoh)
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]
Of ¹ H-NMR analysis and ¹³ C-NMR analysis of the compound, ¹³ C-NMR analysis to determine the respective structural units content and fluorine atom content of the polymer, nuclear magnetic resonance apparatus (JNM-ECX400, manufactured by JEOL ).

<Production of compound>
[Example 1]
Nitrogen-substituted 2,000 mL 3-neck flask was charged with 76.49 g of 2-bromopropionic acid and 500 mL of dichloromethane, and cooled to 0 ° C. in an ice bath. There, 63.5 g of oxalyl chloride was slowly added dropwise so that the internal temperature did not increase, and 0.5 g of dimethylformamide was added dropwise. The mixture was stirred at 0 ° C. for 2 hours, and disappearance of 2-bromopropionic acid was confirmed by GC. Thereafter, a solution obtained by dissolving 40.7 g of hydroxyacetone in 200 mL of dichloromethane was slowly added dropwise so that the internal temperature did not increase, and then a solution of triethylamine 55.7 g in 200 mL of dichloromethane was slowly added dropwise so that the internal temperature did not increase. The mixture was stirred for 2 hours while maintaining the internal temperature at 0 ° C. After confirming the progress of the reaction by TLC check, 500 g of ultrapure water and 500 g of a saturated sodium hydrogen carbonate aqueous solution were added to stop the reaction. The organic layer was collected by a liquid separation operation. After adding 500 mL of 0.1N hydrochloric acid aqueous solution to the organic layer, the organic layer was recovered by liquid separation operation, washed twice with ultrapure water, and concentrated under reduced pressure with an evaporator to recover a crude product. The crude product was distilled under reduced pressure (95 ° C., 1 mmHg) to obtain 93.6 g of 2-oxopropyl 2-bromopropanoate represented by the following formula (a1) (yield 90%).

  To a 2,000 mL three-necked flask purged with nitrogen, 39.2 g of zinc powder and 400 mL of THF were added and stirred to form a suspension. Thereto, 1.5 g of trimethylsilyl chloride was added and stirred for 30 minutes. Thereafter, the internal temperature was raised to 65 ° C. in an oil bath, and a THF 200 mL solution of 83.6 g of the above-synthesized 2-oxopropyl 2-bromopropanoate was dropped therein over 2 hours. The progress of the reaction was confirmed by TLC, the internal temperature was cooled to 23 ° C., and 500 mL of 1N aqueous hydrochloric acid was added to stop the reaction. The organic layer was collected by a liquid separation operation and concentrated under reduced pressure using an evaporator. The residue was dissolved in 300 g of dichloromethane, 200 mL of saturated brine was added, the organic layer was recovered by liquid separation operation, concentrated under reduced pressure using an evaporator, and 4-hydroxy-3,4- represented by the following formula (b1). 38.2 g of a crude product of dimethyl-1-oxa-2-oxo-cyclopentane was obtained (yield 73%).

  A nitrogen-substituted 500 mL three-necked flask was charged with 26.0 g of the synthesized 4-hydroxy-3,4-dimethyl-1-oxa-2-oxo-cyclopentane and 200 mL of acetonitrile, and the internal temperature was adjusted in an ice bath. Was brought to 0 ° C. Thereto, 20.2 g of triethylamine was slowly added dropwise so as not to increase the internal temperature, and then 20.9 g of methacryloyl chloride was slowly added dropwise so that the internal temperature did not increase. Thereto was added 0.1 g of 4-dimethylaminopyridine, the internal temperature was raised to 23 ° C., and the mixture was stirred for 2 hours. The progress of the reaction was confirmed by GC, 100 mL of 1N hydrochloric acid aqueous solution was added, and the organic layer was recovered by liquid separation operation. The collected organic layer was concentrated under reduced pressure using an evaporator, the residue was dissolved in 200 mL of dichloromethane, 100 g of a saturated aqueous sodium hydrogen carbonate solution was added, the organic layer was recovered by a liquid separation operation, and washed twice with ultrapure water. The organic layer was concentrated under reduced pressure using an evaporator, and the recovered crude product was purified by silica gel column chromatography (ethyl acetate / n-hexane = 1/4 (volume ratio)) to obtain the following formula (i-1). 35.7 g of the represented 1,2-dimethyl-3-oxa-4-oxo-cyclopentyl 2-methylpropenoate was obtained (yield 91%).

¹ H-NMR analysis data is shown below.
¹ H-NMR (measurement solvent: CDCl ₃ , reference material: tetramethylsilane) δ: 6.09 (s, 1H), 5.62 (s, 1H), 4.56 (d, 1H), 4.41 (D, 1H), 2.96 (q, 1H), 1.92 (s, 3H), 1.55 (s, 3H), 1.29 (d, 3H)

[Example 2]
In Example 1, the starting material is represented by the following formula (i-2) in the same manner as in Example 1 except that 2-bromo-2-methylpropionic acid is used instead of 2-bromopropionic acid. To yield 49% yield.

¹ H-NMR (measurement solvent: CDCl ₃ , reference material: tetramethylsilane) δ: 6.09 (s, 1H), 5.62 (s, 1H), 4.49 (d, 1H), 4.40 (D, 1H), 1.92 (s, 3H), 1.52 (s, 3H), 1.24 (ds, 6H).

[Example 3]
In Example 1, a compound represented by the following formula (i-3) was produced in the same manner as in Example 1 except that 1-hydroxy-2-butanone was used as a starting material instead of hydroxyacetone. (Yield 56%)

¹ H-NMR (measurement solvent: CDCl ₃ , reference material: tetramethylsilane) δ: 6.09 (s, 1H), 5.62 (s, 1H), 4.57 (d, 1H), 4.42 (D, 1H), 2.90 (t, 1H), 1.92 (s, 3H), 1.54 (s, 3H), 1.20 (m, 2H), 1.12 (t, 3H) .

<Synthesis of polymer>
Monomers other than the produced compound (i) used in the synthesis of [A] polymer and [D] polymer are shown below.

[[A] Synthesis of polymer]
[Example 4]
811 g of the compound (i-1) produced above, 6.89 g of the compound (M-1), and 0.67 g of dimethyl 2,2′-azobis (2-isobutyronitrile) as a radical polymerization initiator were added. -A monomer solution was prepared by dissolving in 30 g of butanone. After charging 15 g of 2-butanone into a 500 mL three-necked flask and purging with nitrogen for 30 minutes, the reaction kettle was heated to 80 ° C. with stirring. The monomer solution prepared above was dropped therein over 4 hours, and after completion of the dropwise addition, the mixture was aged at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization reaction liquid was cooled to 23 ° C. by water cooling. This polymerization reaction liquid was concentrated under reduced pressure using an evaporator until the mass of the polymerization reaction liquid became 45 g. Next, the concentrated polymerization reaction liquid was put into 300 g of methanol, and reprecipitation operation was performed. The slurry containing the precipitated polymer was subjected to suction filtration, the polymer was collected by filtration, and the obtained solid content was washed with methanol three times. The obtained powder was vacuum-dried at 60 ° C. for 15 hours to obtain 12.3 g (yield 82%) of polymer (A-1) as a white powder. Mw of the polymer (A-1) was 6,600, and Mw / Mn was 1.63. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (i-1) and (M-1) were 50.8 mol% and 49.2 mol%.

[Examples 5 to 12 and Synthesis Examples 1 to 5]
The polymers (A-2) to (A-9) and the polymer (CA-1) to the polymer (CA-1) to (CA-5) was synthesized. The total mass of the monomers used was 15 g. “-” In Table 1 indicates that the corresponding monomer was not used. Table 1 shows the content, yield (%), Mw, and Mw / Mn ratio of each structural unit of these polymers.

[[D] Synthesis of polymer]
[Synthesis Example 6]
16.23 g (80 mol%) of the compound (M-17) and 3.77 g (20 mol%) of the compound (M-6) were dissolved in 30 g of 2-butanone, and dimethyl 2, as a polymerization initiator was further dissolved. A monomer solution was prepared by dissolving 0.74 g of 2′-azobisisobutyrate. A 300 mL three-necked flask containing 10 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 4 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. After transferring this polymerization reaction liquid to a 500 mL separatory funnel, the polymerization reaction liquid was uniformly diluted with 150 g of n-hexane, 600 g of methanol was added and mixed, and then 30 g of distilled water was added. The mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered and solvent substitution was performed to obtain a propylene glycol monomethyl ether acetate solution of the polymer (D-1) (yield 60%). Mw of the polymer (D-1) was 6,600, and Mw / Mn was 1.50. As a result of ¹³ C-NMR analysis, the content ratios of the structural unit derived from the compound (M-17) and the structural unit derived from the compound (M-6) were 80.5 mol% and 19.5 mol%, respectively. It was.

<Preparation of photoresist composition>
Each component used for preparation of a photoresist composition is shown below.

[[B] acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium adamantane-1-yloxycarbonyldifluoromethanesulfonate B-2: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane- 1-sulfonate B-3: 4-butoxynaphthalen-1-yltetrahydrothiophenium adamantane-1-yloxycarbonyldifluoromethanesulfonate B-4: triphenylsulfonium 2- (adamantan-1-yl) -1,1- Difluoroethanesulfonate

[[C] acid diffusion controller]
Each structural formula is shown below.
C-1: Triphenylsulfonium 10-camphorsulfonate C-2: N- (undecan-1-ylcarbonyloxyethyl) morpholine C-3: N- (t-amyloxycarbonyl) -4-hydroxypiperidine

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 13]
[A] 100 parts by mass of (A-1) as a polymer, [B] 4.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 8 as an acid diffusion controller 0.7 parts by weight, (D-1) 5 parts by weight as a polymer, and (E-1) 1,981 parts by weight, (E-2) 849 parts by weight and (E) as a solvent. -3) 100 parts by mass was mixed to prepare a photoresist composition (J-1).

[Examples 14 to 24 and Comparative Examples 1 to 5]
Photoresist compositions (J-2) to (J-12) and (CJ-1) to (CJ-5) were obtained in the same manner as in Example 13 except that the components having the types and contents shown in Table 2 were used. ) Was prepared.

<Formation of resist pattern>
Using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a lower antireflection film forming composition (ARC66, manufactured by Brewer Science) was applied, and then heated at 205 ° C. for 60 seconds. As a result, a lower antireflection film having a thickness of 105 nm was formed. Each photoresist composition was applied onto the lower antireflection film using the spin coater, and PB was performed at 100 ° C. for 60 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 90 nm. Next, this resist film is 41 nm in an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON). It exposed through the mask pattern for resist pattern formation of a line and space (1L / 1S). After the exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 3 below. Then, using a 2.38 mass% TMAH aqueous solution, performing paddle development at 23 ° C. for 30 seconds, then rinsing with ultrapure water for 7 seconds, and then spin-drying by shaking off at 2,000 rpm for 15 seconds. A 41 nm line and space (1L / 1S) resist pattern was formed.

<Evaluation>
About the formed resist pattern, each photoresist composition was evaluated by measuring according to the following method. A scanning electron microscope (CG-4000, manufactured by Hitachi High-Technologies) was used for measuring the resist pattern.

[sensitivity]
In the formation of the resist pattern, an exposure amount for forming a 41 nm line and space (1L / 1S) resist pattern was determined as an optimum exposure amount (Eop), and this was defined as sensitivity (mJ / cm ² ). The sensitivity can be evaluated as “good” when it is 40 mJ / cm ² or less, and “bad” when it exceeds 40 mJ / cm ² .

[EL performance]
The above Eop in the range of exposure amount when the pattern dimension resolved when using a 41 nm line and space (1L / 1S) resist pattern forming mask pattern is within ± 10% of the mask design dimension The ratio to the EL (exposure margin) performance (%). As the EL performance value is larger, the change amount of the patterning performance with respect to the exposure amount change is smaller and better. The EL performance can be evaluated as “good” when it is 17% or more, and “bad” when it is less than 17%.

[LWR performance]
The formed resist pattern was observed from above the pattern using the scanning electron microscope. A total of 500 line width variations were measured, and a 3-sigma value was determined from the distribution of the measured values, and this was defined as LWR performance (nm). The smaller the value of the LWR performance, the smaller the line play and the better. The LWR performance can be evaluated as “good” when it is 3.0 nm or less, and “bad” when it exceeds 3.0 nm.

[CDU performance]
The formed resist pattern was observed from above the pattern using the scanning electron microscope. The line width was measured at 20 points in the range of 400 nm, the average value was measured at a total of 500 points, and a 3-sigma value was obtained from the distribution of the measured values, which was taken as CDU performance (nm). The smaller the value of the CDU performance, the better the line width variation over a long period. The CDU performance can be evaluated as “good” when it is 1.5 nm or less, “slightly good” when it exceeds 1.5 nm and 2.0 nm or less, and “bad” when it exceeds 2.0 nm.

[Top loss suppression]
The height of the formed 41 nm line and space (1L / 1S) pattern was measured using a cross-sectional SEM (S4800, manufactured by Hitachi High-Technologies). The height of this pattern was used as an index for suppressing the top loss. The top loss suppression is such that the closer the pattern height is to the film thickness of the resist film, the smaller the top loss and the better the rectangularity of the pattern. The top loss suppression can be evaluated as “good” when the pattern height is 84 nm or more, and “bad” when the pattern height is less than 84 nm.

  Table 3 shows the measured values as evaluation results.

  As is apparent from the results in Table 3, according to the photoresist composition of the example, a fine resist pattern with a small LWR and a small top loss can be formed while exhibiting a wide EL. On the other hand, in the photoresist composition of the comparative example, each performance of EL, LWR, and CDU was insufficient, and the top loss suppression property was also insufficient.

According to the photoresist composition and the resist pattern forming method of the present invention, in the negative pattern formation using a developer containing an organic solvent, a resist pattern with a small LWR and CDU and a small top loss while exhibiting a wide EL. Can be formed. Therefore, the photoresist composition and the resist pattern forming method can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (8)

[A] A polymer having a structural unit (I) represented by the following formula (1), and [B] a photoresist composition containing an acid generator.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied. [A] The photoresist composition according to claim 1, wherein the polymer further has a structural unit (II) represented by the following formula (2).

(In Formula (2), R ⁴ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ⁵ is a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or 3 to 3 carbon atoms. It is a monovalent alicyclic hydrocarbon group of 20. R ⁶ and R ⁷ are each independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent chain having 3 to 20 carbon atoms. It is an alicyclic hydrocarbon group or represents a ring structure having 3 to 20 carbon atoms which is constituted together with carbon atoms to which these groups are combined with each other.)   [A] The polymer further has a structural unit (III) which is a structural unit other than the structural unit (I) and includes at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. The photoresist composition according to claim 1 or 2. [B] The photoresist composition according to claim 1, wherein the acid generator is represented by the following formula (3).

(In Formula (3), R ⁸ is a monovalent group containing an alicyclic structure having 7 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members. R ⁹ is carbon. (It is a fluorinated alkanediyl group having a number of 1 to 10. X ⁺ is a monovalent photodegradable onium cation.) (1) A step of forming a resist film using the photoresist composition according to any one of claims 1 to 4,
(2) A resist pattern forming method comprising: exposing the resist film; and (3) developing the exposed resist film. The polymer which has structural unit (I) represented by following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied. A compound represented by the following formula (i).

(In formula (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ³ is Each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein a plurality of R ³ may be the same or different, provided that at least one R ³ is 1 to 1 carbon atom; 20 is a monovalent hydrocarbon group of 20. k is an integer of 0 to 4. m is an integer of 0 to 4. However, 1 ≦ k + m ≦ 4 is satisfied. (A) A step of obtaining a compound represented by the following formula (b) by a cyclization reaction of the compound represented by the following formula (a), and (B) the following formula (b) obtained in the step (A) The manufacturing method of the compound represented by the following formula (i) which has the process of making the compound represented and the compound represented by the following formula (c) react.

(In the formulas (a), (b), (c) and (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is 1 having 1 to 10 carbon atoms. R ³ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a plurality of R ³ may be the same or different. , At least one R ³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, k is an integer of 0 to 4. m is an integer of 0 to 4, provided that 1 ≦ k + m ≦ 4 is satisfied, Y is a halogen atom, Z is a halogen atom, —OH or —OCOR ′, and R ′ is a monovalent hydrocarbon group having 1 to 20 carbon atoms.)